1. Field of the Invention
The present invention relates to an input position detection-style touch type liquid-crystal display device in which viewing blockade based on light reflected by a touch panel is suppressed so that the device is excellent in display quality.
The present application is based on Japanese Patent Applications No. 2000-21310 and 2000-114817, which are incorporated herein by reference.
2. Description of the Related Art
Heretofore, as shown in FIG. 6, a transmission type liquid-crystal display device or a reflection type liquid-crystal display device is known as a touch type liquid-crystal display device equipped with a touch panel for detecting an input position. The transmission type liquid-crystal display device comprises a liquid-crystal display panel 5, and a touch panel 6. The liquid-crystal display panel 5 includes a pair of transparent substrates 52 and 57 provided with transparent electrodes 53 and 56 respectively, a liquid crystal 55 enclosed and sealed by a sealing member 54 between the pair of transparent substrates 52 and 57, and a pair of polarizers 51 and 58 disposed on front and rear surfaces of the pair of transparent substrates 52 and 57 respectively. The touch panel 6 includes a transparent film 61 provided with a transparent electrode 62, a transparent substrate 65 provided with a transparent electrode 64, and a gap adjusting material 63 for forming a gap through which the transparent film 61 and the transparent substrate 65 are disposed so as to be opposite to each other. The touch panel 6 is disposed on a visual side of the liquid-crystal display panel 5. The reflection type liquid-crystal display device is obtained by adding a light reflection layer 59 represented by the virtual line on the back side, opposite to the visual side, of the transmission type liquid-crystal display device. The interposition of the gap is essential to detection of an input position through achievement of partial contact between the transparent electrodes on the basis of pressing.
Increase of the number of interfaces in the arrangement of the touch panel on the visual side, however, brought interfacial reflection of a large amount of external light. This caused glaring light. Hence, there was a problem that contrast of display light in the liquid-crystal display panel was lowered so that display quality was deteriorated. As shown in FIG. 6, particularly reflection α3′ of external light α3 owing to the interface between each of the transparent electrodes 62 and 64 and the gap in the touch panel was so intensive that viewing blockage was intensified by glaring and lowering of contrast of display light β3 in the liquid-crystal display panel 5.
Incidentally, in the case of transparent electrodes made of indium-tin oxide, the refractive index difference between each of the transparent electrodes and the gap is not smaller than about 1.0, so that more intensive interfacial reflection than surface reflection owing to the liquid-crystal display panel is generated. In order to prevent such interfacial reflection, a proposal to provide an anti-reflection film on the touch panel has been made. In the current circumstances, however, the anti-reflection effect is so poor that the effect of improving display equality has been never obtained correspondingly to increase in the number of production steps.